A supporting and guiding device for power lines 2 is intended for use in association with an excavation tool 15 mounted on a drilling machine 1. The device is formed by at least one supporting branch 4, having spacer elements 3, wherein a cable 16 is inserted into at least one housing in said spacer 3, and at least one supply hose 22 for the at least one line 2. The supply hose 22 contains hydraulic hoses and/or electric cables for signal transmission. The device includes transversal connection elements or cross members 42 which are adapted to support supply hoses 22 and are connected to the branch 4. Cable 16 of branch 4 runs through each spacer 3; also, the same cable 16 is subject to a preload generated by the insertion of at least one tensioning element.